State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, China.
Key Laboratory for Power Machinery and Engineering of MOE, Shanghai Jiao Tong University, Shanghai 200240, China.
Molecules. 2017 Dec 6;22(12):2140. doi: 10.3390/molecules22122140.
CF₃CBrCH₂ (2-bromo-3,3,3-trifluoropropene, 2-BTP) is a potential replacement for CF₃Br; however, it shows conflicted inhibition and enhancement behaviors under different combustion conditions. To better understand the combustion chemistry of 2-BTP, a theoretical study has been performed on its reactions with OH and H radicals. Potential energy surfaces were exhaustively explored by using B3LYP/aug-cc-pVTZ for geometry optimizations and CCSD(T)/aug-cc-pVTZ for high level single point energy refinements. Detailed kinetics of the major pathways were predicted by using RRKM/master-equation methodology. The present predictions imply that the -C(Br)=CH₂ moiety of 2-BTP is most likely to be responsible for its fuel-like property. For 2-BTP + OH, the addition to the initial adduct (CF₃CBrCH₂OH) is the dominant channel at low temperatures, while the substitution reaction (CF₃COHCH₂ + Br) and H abstraction reaction (CF₃CBrCH + H₂O) dominates at high temperatures and elevated pressures. For 2-BTP + H, the addition to the initial adduct (CF₃CBrCH₃) also dominates the overall kinetics at low temperatures, while Br abstraction reaction (CF₃CCH₂ + HBr) and β-scission of the adduct forming CF₃CHCH₂ + Br dominates at high temperatures and elevated pressures. Compared to 2-BTP + OH, the 2-BTP + H reaction tends to have a larger effect on flame suppression, given the fact that it produces more inhibition species.
三氟溴丙烯（CF₃CBrCH₂，2-溴-3,3,3-三氟丙烯，2-BTP）是 CF₃Br 的潜在替代品；然而，在不同的燃烧条件下，它表现出矛盾的抑制和增强行为。为了更好地理解 2-BTP 的燃烧化学，我们对其与 OH 和 H 自由基的反应进行了理论研究。通过使用 B3LYP/aug-cc-pVTZ 进行几何优化和 CCSD(T)/aug-cc-pVTZ 进行高精度单点能精修，详尽地探索了势能面。通过 RRKM/master-equation 方法预测了主要途径的详细动力学。目前的预测表明，2-BTP 中的 -C(Br)=CH₂ 部分最有可能是其燃料性质的原因。对于 2-BTP + OH，在低温下，初始加合物（CF₃CBrCH₂OH）的加成是主要通道，而取代反应（CF₃COHCH₂ + Br）和 H 抽提反应（CF₃CBrCH + H₂O）在高温和高压下占主导地位。对于 2-BTP + H，在低温下，初始加合物（CF₃CBrCH₃）的加成也主导着整体动力学，而 Br 抽提反应（CF₃CCH₂ + HBr）和加合物形成的β断裂形成 CF₃CHCH₂ + Br 在高温和高压下占主导地位。与 2-BTP + OH 相比，由于 2-BTP + H 反应会产生更多的抑制物种，因此它对火焰抑制的影响更大。
